1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method for optimizing the use of packet-resources in a wireless access network.
2. Description of Related Art
In wireless packet-data systems like the General Packet Radio System (GPRS), the legacy network dedicated to voice has been functionally separated from the packet-data network. In CDMA 2000, however, the packet-data features have essentially been added on top of the existing circuit-switched voice system. Under certain circumstances, this can cause serious inefficiencies in the network. Two examples are when an authentication failure is reported at the Mobile Switching Center (MSC) after a data path is set up, and when a mobile station (MS) powers down during a dormant point-to-point protocol (PPP) data session.
In the case of the authentication failure, an authentication center (AC) may be co-located with the MSC or with a Home Location Register (HLR). When an MS attempts to use a packet-data service, the MSC and the Base Station Controller (BSC) serving the MS take steps to allocate a radio traffic channel. In parallel, the BSC begins setting up a data path between the MS and a Packet Data Service Node (PDSN). In many cases, the path between the MS and the PDSN may be set up faster than the authentication is reported to the MSC. If an authentication failure is reported to the MSC after the data path is set up between the MS and the PDSN, the MSC deallocates the radio resources that were allocated to the MS, but presently does not do anything to release the data path.
The data path that remains after the radio resources are released is referred to as a “hanging PPP connection” or a “hanging A10 connection.” A PPP connection is a very expensive network resource; it consumes critical PDSN memory capacity. If there are a large number of authentication failures, then there may be a large number of hanging PPP connections. Each connection is eventually released when a PPP timer expires at the PDSN; however, the timer is typically set for several hours in order to avoid prematurely disconnecting PPP sessions when a user temporarily stops sending or receiving data. Therefore, the PPP resources are needlessly tied up for several hours until the PPP timer expires.
Likewise, a hanging PPP connection may be experienced when an MS powers down during a dormant packet-data session. A dormant packet-data session is one in which a packet-data session has been established, but no data has been exchanged for a long period of time. For example, a user may download information from the PDSN, and then spend a considerable amount of time reading it. Under these circumstances, when an inactivity timer expires, the MSC deallocates the radio traffic channel. The PPP connection, however, is maintained. If the user then requests or sends additional data, the dormant packet-data session is reactivated by reallocating a traffic channel so that the data can be transferred.
If an MS is conducting an active packet-data session, and the user powers down the MS, a message is sent from the BSC to the MSC over the traffic channel notifying the MSC that the MS has powered down. The MSC de-registers the user and sends a response back to the BSC. The BSC notifies the PCF that the user has powered down via the BSC-PCF interface. At reception of the power-down notification from the BSC, the PCF triggers a message to the PDSN indicating that the A10 connection should be released. This way, the PDSN removes any PPP states associated with that user.
A PPP inactivity timer may also be used internally within the PDSN. The timer may be initiated at reception of the power-down command from the PCF. The PDSN would tear down the PPP states only after the timer expires. This provides a grace period to the PDSN, in case the user decides to power up again right away.
However, users often power down their MSs when they finish reading downloaded data, and the PPP session is not reactivated. When the user powers down the MS during a dormant packet-data session, a problem arises because only the radio network is notified that the MS has powered down. The MSC does not know that an instruction needs to be issued to the BSC to release the A10 connection at the PDSN. The PPP connection is left hanging, thus wasting an expensive network resource. As discussed above, the PPP connection is eventually released when the PPP timer expires after several hours, but the resource is needlessly tied up until this occurs.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a system and method for optimizing the use of packet-resources in a wireless access network by eliminating hanging PPP connections. The present invention provides such a system and method.